JP2001179873A - Zinc phosphate composite treated steel panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environment compatible chromium-free surface treated steel panel excellent in corrosion resistance, powdering resistance, lubricity, coating properties and weldability. SOLUTION: A zinc phosphate composite treated steel panel excellent in corrosion resistance, powdering resistance, lubricity and coating properties is obtained by providing a zinc phosphate composite film layer containing at least one element selected from niclel, manganese and magnesium on the surface of a galvanized steel panel in an adhesion amount of 0.3-2.5 g/m2 as a first layer and providing an organic film based on an organic resin on the film layer as a second layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a zinc-based galvanized steel sheet used for automobile bodies and home electric appliances.
Zinc phosphate treated steel sheet, excellent in corrosion resistance, powdering resistance, lubricity, paintability (paint adhesion, electrodeposition coating uniformity of polished part, sharpness), and sealing with chromic acid aqueous solution The present invention relates to an environmentally friendly zinc phosphate composite-treated steel sheet which is not environmentally friendly.

[0002]

2. Description of the Related Art Conventionally, as a surface treated steel sheet for an automobile body, electric Zn-Ni alloy plated steel sheet, organic composite coated steel sheet (electric Zn-Ni alloy plated steel sheet + chromate film +
Organic coatings) and galvannealed steel sheets were mainly used. However, in recent years, car manufacturers have been studying to use cheaper pure galvanized steel sheets as steel sheets for automobile bodies from the viewpoint of cost reduction. However, pure galvanized steel sheet has a problem that the plating layer itself is soft and has a low melting point, so that the plating and the tool are easily welded at the time of press forming, and press cracking or the like occurs in the processing of parts with complicated shapes. The development of an excellent material was required. Therefore, the following technology has been proposed.

[0003] (1) Japanese Patent Application Laid-Open No. Hei 7-138768 (hereinafter referred to as Prior Art 1) discloses that zinc and phosphorus are formed on a surface of a zinc-containing metal-plated steel sheet at a specific weight ratio and a specific metal is specified. Having a zinc phosphate coating layer containing a weight ratio,
A zinc phosphate treated steel sheet further having a lubricating oil layer thereon has been proposed.

(2) Japanese Patent Application Laid-Open No. 09-049086 (hereinafter referred to as Prior Art 2) discloses that an electrogalvanized steel sheet is made of phosphate ion, zinc ion, magnesium ion,
There is disclosed a method for producing an electroplated steel sheet having high whiteness and excellent coatability, wherein the treatment is performed under specific processing conditions using a processing liquid containing nickel ions or the like at a specific content.

However, although the zinc phosphate treated steel sheets disclosed in the above prior arts 1 and 2 show some improvement in lubricity, the improvement effect is not at a satisfactory level. Due to the porous structure of the film, it is difficult for the electrodeposition coating to turn around, such as inside the mating flange or hemming part of the car body, and corrosion resistance in areas where the steel sheet is likely to be exposed even after the electrodeposition coating Was inferior. Further, the electroplated steel sheet manufactured by the technique disclosed in the above prior art 2 has a sufficient level of paint adhesion and corrosion resistance after coating under a multilayer coating of two or more coats applied to a steel sheet for an automobile body. It was not something.

As a technique for improving the corrosion resistance of a zinc phosphate-treated steel sheet, a post-treatment called sealing treatment with a chromic acid-based aqueous solution is conventionally performed after zinc phosphate treatment in the field of steel sheets for household appliances. I was However, in this conventional sealing technology for zinc phosphate treated steel sheets, since it contains hexavalent chromium, which is an environmentally regulated substance, it is desired to develop a technology that does not contain chromium, and the following technologies have been proposed.

(3) JP-A-56-136979 (hereinafter referred to as Prior Art 3) discloses that a cold-rolled steel sheet and a galvanized steel sheet are subjected to a phosphate treatment and immediately thereafter contain a chelating agent as a main component. A post-treatment method has been proposed.

(4) JP-A-58-197284 (hereinafter referred to as Prior Art 4) discloses that an aqueous solution containing polyacrylic acid and an aromatic polyhydric alcohol after subjecting a galvanized steel sheet to a phosphate treatment. There has been proposed a method for pre-painting a zinc-based plated steel sheet, which is characterized in that the method is applied.

(5) JP-B-63-4916 (hereinafter referred to as Prior Art 5) has a phosphate film of 1-2 g / m ² on a Zn-Ni alloy plating, and further has an upper layer. A highly durable composite plated steel sheet having a polymer film of 5 to 10 μm has been proposed.

[0010]

However, each of the above-mentioned conventional zinc phosphate composite-treated steel sheets has the following problems.

In other words, the zinc phosphate treated steel sheets shown in the prior arts 3 and 4 do not have the paint adhesion at the level required for a steel sheet for automobiles because they use a normal zinc phosphate film. . Further, in the organic sealing disclosed in these prior arts, contact with an alkali or acid solution in an assembly process of an automobile body (shear → press → welding → alkali degreasing → chemical formation → electrocoating → middle / overcoating) As a result, the film is dissolved or deteriorated, so that the corrosion resistance was inferior.

[0012] The zinc phosphate treated steel sheet shown in the prior art 5 uses a normal zinc phosphate film, similar to the above prior arts 3 and 4, and therefore has the level of paint adhesion required for a steel sheet for automobiles. Do not have. In addition, since the thickness of the organic film is as large as 5 to 10 μm, not only welding by spot welding is difficult, but also the film is easily peeled off by bending back at a bead portion during press molding (that is, powdering resistance). Inferior properties), the exfoliated material deteriorates lubricity, so that press formability was also poor.

Further, in the case of a steel plate for an automobile body outer panel, when a die is damaged and a surface defect is present in a pressing step, the surface of the vehicle body may be polished and repaired for the purpose of beautifying the surface. Therefore, when the zinc phosphate treated steel sheet shown in the above prior arts 1 to 5 is used as a steel sheet for an automobile body outer panel, the electrodeposition characteristics of the polished portion and the unpolished portion are greatly different, so the There is a problem that a large difference is generated and uniform finish of coating is not obtained. In addition, even in a normal film portion (unpolished portion) not polished, the sharpness after three coats was inferior.

Therefore, the present invention has been made in view of such problems of the prior art, and has been made in consideration of corrosion resistance (unpainted corrosion resistance,
Environmentally friendly surface that is excellent in corrosion resistance after painting), powdering resistance, lubricity, paintability (paint adhesion, electrodeposition coating uniformity of polished part, sharpness) and weldability, and does not contain chrome. It is intended to provide a treated steel sheet.

[0015]

Means for Solving the Problems The present inventors have conducted intensive studies on the relationship between the coating composition of the zinc phosphate composite treated steel sheet and its corrosion resistance, powdering resistance, lubricity, paintability and weldability. As a result, the following findings were obtained.

(1) In order to improve corrosion resistance, lubricity, and paintability, a specific zinc phosphate film is formed on the surface of a zinc-based plated steel sheet as a base, and a specific organic resin containing a specific organic resin as a main component is formed thereon. It is effective to have a two-layer structure provided with an organic film.

(2) By adding a specific rust preventive additive to the organic film at a specific content, the corrosion resistance is further improved without deteriorating the lubricity, paint adhesion and weldability.

(3) By adding a specific lubricant in a specific content to the organic film, the lubricity is further improved without deteriorating the corrosion resistance, paint adhesion and weldability.

(4) Lubricity, corrosion resistance, paintability, weldability, powdering resistance by optimizing the coating weight of the zinc phosphate composite coating layer and the coating weight of the organic coating layer thereon. The performance is improved.

The present invention has been made based on such findings, and is characterized by having the following configuration.

[0021] The present invention, on the surface of the galvanized steel sheet, nickel as a first layer, phosphorus deposition amount 0.2~2.5g / m ² which contains at least one selected from the group consisting of manganese and magnesium A corrosion-resistant, powdering-resistant, lubricating, and coating material having a zinc oxide composite film layer and an organic film mainly composed of an organic resin shown in the following (1) as a second layer thereon. To provide a zinc phosphate composite treated steel sheet having excellent heat resistance.

(1) To a modified epoxy resin (A) comprising an epoxy resin, a polyfunctional amine and a monoisocyanate, a block urethane (B) comprising a polyol, a polyisocyanate and a blocking agent is mixed with A / B = 95/5.
A block urethane-modified epoxy resin mixed at a ratio of 50/50 (weight ratio of nonvolatile components).

In the present invention, the content of at least one selected from nickel, manganese and magnesium contained in the zinc phosphate composite coating is 0.5 to 8.5% by mass in total. Is preferred.

[0024] The organic coating may be a rust preventive additive and / or
Or a solid lubricant, and a preferable content of the rust preventive additive is 1 to 100 parts by weight based on 100 parts by weight of the block urethane-modified epoxy resin in solid content. The preferred content is 1 to 8 based on 100 parts by weight of the block urethane-modified epoxy resin in solid content.
0 parts by weight.

Further, in the present invention, it is preferable that the rust preventive additive contains hydrophilic silica, and that the rust preventive additive contains silica having a specific surface area of 20 to 1000 m ² / g.

The solid lubricant is preferably at least one selected from polyethylene wax (preferably having a softening point of 100 to 135 ° C.), tetrafluoroethylene resin and boron nitride. The average particle size of the solid lubricant is preferably 0.05 to 25 μm.

Further, when the amount of the organic film adhered is 0.0
It is preferably from ⁵ to 1.5 g / m2.

In the present invention, the outermost layer preferably has a rust-preventive oil film layer having an adhesion amount of 0.01 to 10 g / m ² .

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below together with the reasons for limiting the same.

The steel sheet used as the substrate of the galvanized steel sheet used in the present invention includes cold-rolled steel sheets for general working (CQ) to cold-rolled steel sheets for deep drawing (DQ) and cold-rolled steel sheets for deep and deep drawing (DD).
Q), all cold-rolled steel sheets for soft working up to ultra deep drawing cold-rolled steel sheets (EDDQ), from high-strength steel sheets with a relatively low strength level with bake hardenability to general high-tensile steel sheets exceeding 390 MPa All high-strength steel sheets and descaled hot-rolled steel sheets can be used.

As a plating layer of a zinc-based plated steel sheet, Z
n plating, Zn-Ni alloy plating (Ni content 9 to 15)
Mass%), Zn-Fe alloy plating (Fe content 5 to 25)
Mass% or 60 to 90 mass%), Zn-Mn alloy plating (Mn content 30 to 80 mass%), Zn-Co alloy plating (Co content 0.5 to 15 mass%), Zn-Cr alloy plating ( Cr content: 5 to 30% by mass); Zn-Al alloy plating (Al content: 3 to 60% by mass). In addition, Co, Fe, Ni, Cr
And the like, oxides such as silica, alumina and hardly soluble chromate, salts, polymers and the like. Further, it is also possible to form a multilayer plating in which two or more of the same or different types of the above-mentioned plating layers are plated.

The plated steel sheet may be one in which the steel sheet is preliminarily plated with a thin coating of Ni or the like, and then the above-described various platings are applied thereon. These platings
It can be formed by any of an electrolytic method, a melting method, and a gas phase method. The coating weight is preferably 10 g / m ² or more. If the coating weight is less than 10 g / m ² , there is a problem because the corrosion resistance is poor. Also, Zn-Ni alloy plating, Zn-Fe alloy plating, Zn-Mn alloy plating, Zn-Co alloy plating, in the case of Zn-Cr alloy plating, since the powdering resistance is inferior and when it exceeds 60 g / m ^2, It is preferable that the plating adhesion amount is 10 to 60 g / m ² . Further, in order to secure higher corrosion resistance and powdering resistance, the plating adhesion amount is 15 to 60 g / m ^2.
It is preferable that

Further, when a zinc phosphate composite film described later is formed on the plating film surface, in order to prevent the occurrence of film defects and unevenness, if necessary, alkali degreasing, solvent degreasing, etc. Surface conditioning treatment (for example,
(1) treatment with an acidic or alkaline aqueous solution containing at least one metal ion selected from Ni ions, Co ions, Fe ions, and Zn ions; (2)
(3) Etching the upper layer of the metal oxide formed on the surface of the plated steel sheet using a chelating compound such as an inorganic acid, an organic acid, EDTA, or NTA). It is also possible to give. As described above, the effects of the present invention can be obtained when any of these steel plates is used as the substrate.

The zinc phosphate composite-treated steel sheet according to the present invention comprises:
A zinc phosphate film is formed as a first layer on the zinc-based plated steel sheet, and an organic film is formed as a second layer on the zinc phosphate film. The first layer of zinc phosphate film is
The anchor effect improves paint adhesion, and also prevents lubrication by preventing direct contact between the steel plate and the tool during sliding.

In the present invention, a zinc phosphate film containing at least one selected from nickel, manganese and magnesium is used. This film is presumed to be present in a form in which a part of zinc in the zinc phosphate film has been replaced with the above-mentioned metal contained in the film.
Interaction with the organic layer as the upper layer works to provide excellent corrosion resistance, powdering resistance, lubricity, and paint adhesion.

The preferred content of at least one selected from nickel, manganese and magnesium in the zinc phosphate coating is 0.5 to 8.5% by mass in total. By setting the total content of these metals in the coating within the above range, corrosion resistance, lubricity, and paint adhesion are further improved. When particularly excellent corrosion resistance and paint adhesion are required, the total content of nickel, manganese or magnesium is more preferably 2.5 to 7% by mass. Furthermore, in this case, corrosion resistance and paint are obtained by containing nickel as an essential component in the range of 1 to 5.5% by mass and containing manganese and / or magnesium in a total range of 0.5 to 4% by mass. Adhesion improves in each step.

The amount of the zinc phosphate composite film as the first layer is preferably in the range of 0.2 to 2.5 g / m ² . When the amount of adhesion is less than 0.2 g / m ² , paint adhesion and corrosion resistance are inferior. When the amount exceeds 2.5 g / m ² , powdering at the time of sliding increases and not only deteriorates lubricity, but also
Poor spot weldability, uniformity of electrodeposition coating on the polished part, and sharpness. From the viewpoints of lubricity, paintability, corrosion resistance, and weldability, a more preferable adhesion amount range is 0.5 to 2.0 g / m ² , and most preferably 0.7 to 1.5 g / m ² .

As the zinc phosphate treatment method for forming the zinc phosphate film layer, it can be formed by any of a reaction type treatment, a coating type treatment and an electrolytic type treatment.

As the reaction-type treatment, for example, after a coated steel sheet is subjected to degreasing, water washing and surface conditioning treatment, at least one selected from nickel, manganese and magnesium ions together with phosphate, nitrate and zinc ions. It can be formed by bringing an aqueous solution containing one kind as a main component into contact with a treatment liquid obtained by adding the following (1) and (2) as necessary, washing with water, and drying.

(1) At least one selected from iron ions, cobalt ions and calcium ions (2) At least one selected from peroxides, fluoride ions, complex fluoride ions and nitrite ions.

As the coating type treatment, a zinc phosphate treatment solution containing at least one selected from nickel, manganese and magnesium ions together with phosphate, nitrate and zinc ions is applied to a plated steel sheet. At least on one side. The coating method is optional, and in addition to coating by a roll coater method, it is also possible to adjust the coating amount by an air knife method or a roll drawing method after coating by a dipping method or a spray method. A zinc phosphate coating can be formed by applying a zinc phosphate treatment solution to the surface of a plated steel sheet and then drying it using a dryer, a hot air oven, a high-frequency induction heating oven, or an infrared oven. When forming a film by the coating type treatment, the film drying temperature is preferably from 70 to 400 ° C. at the ultimate plate temperature. When the drying temperature is lower than 70 ° C., the drying of the coating is insufficient, and not only the stickiness of the coating and the deterioration of the paint adhesion are caused, but also the unevenness of the coating when the second organic coating is formed. On the other hand, if the ultimate plate temperature exceeds 400 ° C., no further effect can be obtained, which is not only uneconomical, but also tends to cause defects in the coating film, resulting in poor corrosion resistance. From such a viewpoint, the more preferable baking temperature is 100 to 300 ° C, and more preferably 120 to 170 ° C.
It is.

Next, the organic film formed on the zinc phosphate composite film will be described. In the present invention, the organic film formed on the zinc phosphate film layer is a modified epoxy resin (A) composed of an epoxy resin, a polyfunctional amine and a monoisocyanate, and a block urethane (a polyol, a polyisocyanate and a blocking agent). B) is mixed with A / B at a ratio of 95/5 to 50/50 (weight ratio of non-volatile components) to form a block urethane-modified epoxy resin as a main component.

As the epoxy resin, an epoxy resin obtained by glycidyl etherification of bisphenol A, bisphenol F, novolak, or the like; an epoxy resin obtained by adding propylene oxide or ethylene oxide to bisphenol A and glycidyl etherification can be used. Further, aliphatic epoxy resin, alicyclic epoxy resin, polyether epoxy resin can also be used,
Two or more of these epoxy resins can be used in combination. Epoxy resins having an epoxy equivalent of 400 or more are preferred from the viewpoint of corrosion resistance. The modified epoxy resin (A) in the present invention is obtained by modifying these epoxy resins with a polyfunctional amine and a monoisocyanate. Modification of an epoxy resin with a polyfunctional amine is obtained by reacting a glycidyl group of the epoxy resin with a polyfunctional amine. Examples of the polyfunctional amine include primary alkanolamines such as ethanolamine, propanolamine, isopropanolamine, and butanolamine. Propylamine,
Primary alkylamines such as butylamine, octylamine and decylamine; ethylenediamine, diethylenetriamine, tetraethylenepentamine, xylenediamine,
Examples thereof include those having two or more active hydrogens in one molecule such as aminoethylpiperazine and norbornanediaminomethyl, and the use of two or more of these amines is also possible. Alkanolamine is preferred from the viewpoint of corrosion resistance and paint adhesion.

By modifying the epoxy resin with a monoisocyanate, the corrosion resistance can be further improved.
As the monoisocyanate, those obtained by reacting phosgene with an aliphatic monoamine or an aromatic monoamine can be used. Further, one obtained by reacting one isocyanate group of a diisocyanate compound with an aliphatic alcohol, an aromatic alcohol, or an alicyclic alcohol can also be used. Here, as the alcohol, an alcohol having 4 or more carbon atoms is preferable from the viewpoint of compatibility with the epoxy resin. Examples of the diisocyanate include aliphatic isocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; aromatic isocyanates such as xylylene diisocyanate, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate; isophorone diisocyanate and norbornane diisocyanate There are alicyclic isocyanates such as methyl and the like, and these can be used as a mixture of two or more kinds.

As an example of the synthesis of the modified epoxy resin (A), the active hydrogen of the polyfunctional amine is mixed with the glycidyl group of the epoxy resin in an amount equivalent to 1.1 to 1.8 times, and the mixture is mixed. C. for 4 to 10 hours, and further added monoisocyanate in an amount equivalent to 0.7 to 2.0 times the active hydrogen of the remaining amine,
There is an example in which the reaction is continued at 00 ° C.

The block urethane of the present invention is a compound obtained by protecting an inactive isocyanate group of an isocyanate compound with a suitable compound and rendering it inactive. When heated, the blocking agent is dissociated and the activity of the isocyanate group is easily regenerated. Is what you do. That is, it has a role as a curing agent for the modified epoxy resin.

As the polyol, dihydric alcohols such as ethylene glycol, propylene glycol, 1,6-hexanediol, diethylene glycol and triethylene glycol; trihydric alcohols such as glycerin and trimethylolpropane; low molecular polyols such as pentaerythritol; Polyester polyols obtained from capractone or low molecular weight polyols and dicarboxylic acids; high molecular weight polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like having a molecular weight of 400 or more, and combinations of two or more of these polyols It is also possible. here,
When a high molecular weight polyol is used as the polyol, a moderate hydrophilicity is imparted to the organic film. As a result, the compatibility with the cationic electrodeposition paint is improved, and a smooth electrodeposition surface is obtained.
Excellent sharpness after overcoating and excellent uniformity of electrodeposition coating in the polished part can be obtained.

As the polyisocyanate, all of the above-mentioned diisocyanates, mixtures thereof, and polynuclear compounds can be used. Examples of the blocking agent include phenol compounds such as phenol; lactam compounds such as ε-caprolactam; oxime compounds such as methyl ethyl ketoxime; and imine compounds such as ethyleneimine. It is also possible to use Block urethane (B is used to synthesize a prepolymer by mixing and reacting the two so that the isocyanate group of the polyisocyanate is excessive with respect to the hydroxyl group of the polyol, and further protect the remaining isocyanate group of the prepolymer with a blocking agent. The preferable reaction temperature is 30 to 100.
° C.

The block urethane-modified epoxy resin comprises the above-mentioned modified epoxy resin (A) and block urethane (B)
Can be obtained by mixing The mixing ratio is A / B = 95/5 to 50/50 by weight ratio of nonvolatile components.
Range. The ratio of the modified epoxy resin (A) is 95 /
If it exceeds 5, the sharpness after the middle / overcoating and the uniformity of the electrodeposition coating in the polished part are deteriorated, while the modified epoxy resin (A)
Is less than 50/50, the corrosion resistance deteriorates. Further, in order to obtain a higher degree of sharpness, uniformity of electrodeposition coating in the polished portion, and corrosion resistance, A / B = 90/10 to 60/40.
Is preferable.

In the present invention, a rust-preventive additive or a solid lubricant can be blended in the organic film as required, or even better performance can be obtained by blending both. Can be.

In the present invention, the rust-preventive additive contained in the organic coating is preferably 1 to 100 parts by weight of the above-mentioned block urethane-modified epoxy resin in a weight ratio of non-volatile components.
By blending 100 parts by weight, more excellent corrosion resistance and coatability can be imparted.

When the amount of the rust-preventive additive is less than 1 part by weight based on 100 parts by weight of the block urethane-modified epoxy resin, the effect of improving the corrosion resistance is not sufficient. Poor powdering and lubricity. The amount is particularly preferably from 10 to 80 parts by weight, more preferably from 20 to 70 parts by weight, from the viewpoint of obtaining higher corrosion resistance, lubricity, powdering resistance and paint adhesion.

Suitable rust preventive additives for use in the present invention include silica, phosphates, molybdates, phosphomolybdates (eg, aluminum phosphomolybdate, etc.),
Organic phosphoric acid and salts thereof (for example, phytic acid, phosphonic acid and their metal salts, alkali metal salts, alkaline earth metal salts), organic inhibitors (for example, hydrazine derivatives, thiol compounds) and the like; Species or two or more can be used. Among these, it is more preferable to use silica from the viewpoints of corrosion resistance and paintability.

The silica that can be used in the present invention includes dry silica (for example, AEROS manufactured by Nippon Aerosil Co., Ltd.).
IL 130, AEROSIL 200, AEROSI
L300, AEROSIL 380, AEROSIL
972, AEROSILR811, AEROSILR
805, etc.), and organosilica sols (eg, MA-CT, IPA-ST, NBA-S manufactured by Nissan Chemical Industries, Ltd.)
T, IBA-ST, EG-ST, XBA-ST, ETC
-ST, DMAC-ST, etc.), sedimentation wet silica (for example, T-32 (S), K-41, F manufactured by Tokuyama Soda Co., Ltd.)
-80 etc.), gel wet silica (for example, Syloid 244, Syloid 15 manufactured by Fuji Devison Chemical Co., Ltd.)
0, thyroid 72, thyroid 65, SHIELDE
X etc.). In addition, the above silica
It is also possible to use a mixture of more than one species.

[0055] ) Is replaced with a methyl group or the like, the hydrophobic silica whose surface has been hydrophobized is added to the epoxy resin, the compatibility between the organic film and the cationic electrodeposition paint, which is an aqueous paint, becomes poor, resulting in a smooth electrodeposition. Since a coated surface cannot be obtained, the sharpness after the middle and upper coatings and the uniformity of the electrodeposition coating in the polished portion are poor. Therefore, in order to obtain excellent sharpness and uniformity of electrodeposition coating in the polished portion, silica whose surface is not hydrophobized (hydrophilic silica) is more preferable. In the present invention, as a method for further improving the anticorrosive effect of silica, cations having a corrosion inhibitory effect on silica (for example, calcium, zinc, cobalt, lead, strontium, lithium,
Silica ion-exchanged with barium, manganese, or the like can be used. These cations exchange with protons in a corrosive environment and are released from silica to form stable corrosion products on the metal surface,
It is considered that corrosion is suppressed.

The silica that can be used in the present invention preferably has a specific surface area in the range of ²⁰ to 1000 m ² / g (BET method). When the specific surface area is less than 20 m ² / g, the effect of improving the corrosion resistance is poor, and the smoothness of the electrodeposition coated surface is reduced, and the sharpness and the uniformity of the electrodeposition coating in the polished portion are deteriorated. On the other hand, when the specific surface area exceeds 1000 m ² / g, the thixotropic property of the coating composition to which silica is added becomes strong, and the workability when applying with a roll coater or the like is reduced.

In the present invention, a solid lubricant is preferably contained in the organic coating at a weight ratio of 1 to 80 parts by weight based on 100 parts by weight of the above-mentioned block urethane-modified epoxy resin.
By blending parts by weight, more excellent lubricity and powdering resistance can be imparted.

If the amount of the solid lubricant is less than 1 part by weight per 100 parts by weight of the block urethane-modified epoxy resin, no improvement in lubricity and powdering resistance is observed, and if it exceeds 80 parts by weight, paint adhesion and corrosion resistance are not obtained. , And paintability deteriorates. From the viewpoints of paint adhesion, lubricity, corrosion resistance, and paintability, a particularly preferred amount is 5 to 50 parts by weight, and more preferably 15 to 35 parts by weight.

Examples of the solid lubricant that can be suitably used in the present invention include the following.

(1) Polyolefin wax, paraffin wax: for example, polyethylene wax, synthetic paraffin, natural paraffin, microwax, chlorinated hydrocarbon, etc. (2) Fluororesin wax: For example, polyfluoroethylene resin (polytetrafluoroethylene) Resins, etc.), polyvinyl fluoride resins, polyvinylidene fluoride resins, etc. (3) fatty acid amide compounds: for example, stearamide, palmitic amide, methylene bisstearamide, ethylenebisstearamide, oleic amide,
(4) Metal soaps: for example, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc. (5) Metal sulfides: for example, molybdenum disulfide, tungsten disulfide (6) Others: For example, graphite, fluorinated graphite, boron nitride and the like.

When particularly excellent lubricity is required,
It is preferable to use at least one selected from polyethylene wax, polytetrafluoroethylene resin, and boron nitride. In addition, by using a polyethylene wax and a polytetrafluoroethylene resin in combination, particularly excellent lubricity can be obtained.

In the present invention, the solid lubricant preferably has an average particle size of 0.05 to 25 μm. When the average particle size is less than 0.05 μm, the surface area of the lubricant is increased to increase the area occupied by the outermost layer of the organic film, thereby deteriorating paint adhesion. On the other hand, when the average particle size exceeds 25 μm, not only the sharpness is deteriorated due to the fine irregularities on the film surface, but also the lubricity due to the lubricant falling off from the organic film,
Deterioration also occurs in corrosion resistance. Especially excellent clarity, corrosion resistance,
To obtain lubricity and powdering resistance, the average particle size should be 1
To 15 μm, more preferably 3 to 10 μm.

Further, the softening point of polyethylene wax is set to 1
00 ° C to 135 ° C, more preferably 110 ° C to 130 ° C
By setting the temperature to ° C, lubricity and powdering resistance are further improved.

The organic film of the present invention comprises the above-mentioned organic resin,
Rust-preventive additives and solid lubricants are the main components. In addition, as long as they do not adversely affect the quality performance, organic resins other than the above-mentioned resins (for example, acrylic resin, urethane resin, alkyd resin, Fluorine resin, acrylic silicone resin, silicone resin, phenol resin, melanin resin, amino resin), oxide fine particles such as alumina and zirconia, conductive substance, coloring pigment (for example, condensed polycyclic organic pigment, phthalocyanine resin) One or more kinds of organic pigments, coloring dyes (eg, azo dyes, azo metal complex dyes, etc.), film forming aids, dispersibility improvers, defoaming agents and the like can be blended. is there.

The coating amount of the organic coating is 0.05 to 1.
It is preferably 5 g / m ² . The coating weight is 0.0
If it is less than 5 g / m ² , corrosion resistance and lubricity are inferior, and 1.5 g / m ²
If it exceeds m ² , the weldability, the uniformity of electrodeposition coating on the polished portion, and the sharpness will deteriorate. Lubricity, corrosion resistance, weldability, electrodeposition coating uniformity of the polished portion, particularly preferable adhesion amount from the viewpoint of sharpness,
0.2 to 1.0 g / m ² , more preferably 0.1 g / m ² .
3 to 0.7 g / m ² .

In the method of forming an organic film according to the present invention, for example, a coating composition obtained by dissolving or dispersing the above-mentioned components in an organic solvent is applied to at least one surface of a steel sheet having the zinc phosphate film formed thereon. And a film is formed by drying.

An organic solvent is contained in the coating composition to be applied.
By containing 0 to 95% by mass, it is possible to apply a uniform thin film of the paint. If the solvent content of the coating composition is less than 70% by mass, the viscosity of the coating composition is high and the thixotropic property is strong, so that it is difficult to apply a uniform thin film of the coating composition, and there is a problem in coating workability. 95% by mass
If it exceeds, the solid content concentration of the coating material becomes unnecessarily low, so that it becomes difficult to obtain a predetermined adhesion amount when applying with a roll coater or the like. The organic solvent that can be used in the coating composition in the present invention includes diacetone alcohol and / or
Alternatively, an organic solvent containing diethylene glycol monobutyl ether is preferable.

The reason is as follows. That is,
In the present invention, in order to obtain excellent clarity, silica whose surface is not hydrophobized (hydrophilic silica) is used as a rust preventive additive for the specific block urethane-modified epoxy resin described above.
Is most preferable, but when a large amount of silica whose surface is not hydrophobized is added to the coating composition, the viscosity of the coating becomes extremely high, and unevenness is likely to occur when a thin film is applied by a roll coater or the like. Problems arise. As a method of lowering the viscosity of the paint, it is generally conceivable to use a solvent having a high hydrogen bonding property, for example, water or an alcohol solvent, but these are polar solvents for the block urethane-modified epoxy resin used in the present invention. Is too high to dissolve and cannot be used. In addition, even when a ketone-based organic solvent is used in combination with water or an alcohol-based solvent for the purpose of imparting solubility to the block urethane-modified epoxy resin, use of water or an alcohol-based solvent within a range in which the solubility can be maintained. Since the amount is limited, the effect is insufficient to reduce the viscosity and cannot be applied to the coating composition used in the present invention.

Then, as a result of examining the solvent type, diacetone alcohol and / or diethylene glycol monobutyl ether were soluble in the block urethane-modified epoxy resin used in the present invention and prevented the viscosity of the coating from increasing. I found something to do. In other words, by using these solvents, even when a large amount of silica whose surface is not hydrophobized is added to the coating composition, the viscosity of the coating does not increase, and a uniform thin film can be applied by a roll coater or the like. Becomes This is because these solvents have a carbonyl group or an ether group in the molecule, so that they have solubility in the block urethane-modified epoxy resin used in the present invention, and the primary hydroxyl group has a silanol on the silica surface. It is considered that the formation of a three-dimensional knitted state structure by agglomeration of silica is caused by hydrogen bonding to the group and steric hindrance of these solvent molecules.

It is preferable that diacetone alcohol and / or diethylene glycol monobutyl ether be contained in an organic solvent of the coating composition in an amount of 50% by mass or more. 5
If the amount is less than 0% by mass, the effect of suppressing the increase in viscosity of the sample becomes insufficient, and unevenness is likely to occur when a thin film is applied by a roll coater or the like. In consideration of economy, other inexpensive organic solvents (eg, xylene, cyclohexane, isopropyl glycol, etc.) can be used together in a range of less than 50% by mass.

It is possible to arbitrarily perform a pretreatment such as washing with water and drying on the steel sheet on which the zinc phosphate film has been formed as a pretreatment before applying the coating composition.

The method of applying the coating composition to the steel sheet is optional. Usually, the coating is performed by a roll coater method, but it is also possible to adjust the coating amount by an air knife method or a roll drawing method after coating by a dipping method or a spray method.

The drying after applying the coating composition is as follows.
The drying can be performed using a dryer, a hot blast stove, a high-frequency induction heating furnace, or an infrared stove.

The drying temperature is preferably from 50 to 250 ° C. at the ultimate plate temperature. If the drying temperature is lower than 50 ° C., the film is insufficiently dried, causing stickiness of the film, and the film is damaged when the roll is touched after drying, resulting in poor paint adhesion, corrosion resistance, and lubricity. When the reached plate temperature exceeds 250 ° C., not only the coating property is deteriorated, but also the production cost is disadvantageous. From such a viewpoint, a more preferable baking temperature is 80 to 20.
The temperature is 0 ° C, more preferably 100 to 140 ° C.

The present invention includes a steel sheet having the above-mentioned coating structure on both sides or one side. Therefore, aspects of the present invention include, for example, the following.

(1) One side: steel plate surface + zinc phosphate composite film + organic film one surface: steel plate surface + zinc phosphate composite film (2) One surface: steel plate surface + zinc phosphate composite film + organic film one surface: steel plate Surface (3) Both surfaces: steel plate surface + zinc phosphate composite film + organic film In the present invention, a rust-preventive oil layer can be further provided on the organic film layer. Examples of the rust preventive oil include a rust inhibitor (for example, an oil-soluble surfactant), a petroleum base (for example, a mineral oil and a solvent), an oil film conditioner (for example, a mineral oil, a crystalline substance, and a viscous substance), and an oxidant. Typical rust-preventing oils, cleaning rust-preventing oils, lubricating rust-preventing oils and the like, which mainly contain an inhibitor (for example, a phenolic antioxidant) and a lubricating oil (for example, an extreme pressure additive). Usual rust preventive oils include fingerprint-removable rust preventive oil in which the base is dissolved and decomposed in a petroleum solvent, solvent-diluted rust preventive oil, petrolactam, lubricating oil based rust preventive oil based on wax, And vaporizable rust preventive oils.

The coating amount of the rust preventive oil film layer is 0.01
It is preferably from 10 to 10 g / m ² . Adhesion amount 0.01
At less than g / m ² , the effect of attaching the rust preventive oil cannot be obtained,
If the amount exceeds 10 g / m ² , the degreasing becomes poor and the paint adhesion is poor. In order to obtain more excellent corrosion resistance and paint adhesion, it is more preferable that the adhesion amount is 0.5 to 3 g / m ² . The surface-treated steel sheet of the present invention can be applied not only to automobiles and home appliances, but also to applications such as building materials.

[0078]

Example: Plate thickness 0.7 mm, surface roughness (Ra) 1.0 μ
m of a cold-rolled steel sheet, and a zinc-based plating was applied thereto to prepare a plated steel sheet. The plated steel sheet was subjected to alkali degreasing, water washing, and surface conditioning treatment, and then contacted with a zinc phosphate treatment liquid, washed with water, and dried to prepare a zinc phosphate treated steel sheet. Next, the coating composition was applied to the zinc phosphate-treated steel sheet using a roll coater, dried without washing with water, and then coated with a rust-preventive oil or a cleaning oil. For the surface-treated steel sheet thus obtained, lubricity, powdering resistance, corrosion resistance (no coating corrosion resistance, corrosion resistance after painting), paintability (paint adhesion, electrodeposition coating uniformity of the polished part, sharpness) ), Each test of weldability. Specific conditions are as shown below.

(1) Plated Steel Sheet The plating type and the coating weight of the zinc-based plated steel sheet used in this example are shown in Table 2 below.

(2) Zinc phosphate composite treatment The coated steel sheet was degreased and washed with water to clean the surface, and then the surface conditioning liquid, the chemical composition of the zinc phosphate treatment liquid, the treatment temperature, the treatment time, and the adhesion were adjusted. Table 3 with different amounts and coating compositions
Was prepared. The following is an example of a method for producing a zinc phosphate-treated steel sheet. [Zinc phosphate composite coated steel sheet 1] Degreasing (FCL4480
(Nippon Parkerizing Co., Ltd.), 18 g / liter (hereinafter referred to as L), 45 ° C., sprayed for 120 seconds, and then washed (20 seconds, sprayed) with a plated steel sheet (A in Table 2). It was immersed in the zinc phosphate treatment liquid 1 shown in Table 1 heated to 50 ° C. for 10 seconds, washed with water, and dried.
A zinc phosphate composite coated steel sheet 1 was prepared.

[Zinc phosphate composite coated steel sheet 2] Degreasing (FC
L4480 (manufactured by Nippon Parkerizing Co., Ltd.), 18 g
/ L, 45 ° C, sprayed for 120 seconds), then washed with water (20
Seconds, sprayed), a surface conditioning treatment (Preparen Z (manufactured by Nippon Parkerizing Co., Ltd.), 1.5 g / L, room temperature, sprayed for 2 seconds) is performed on the plated steel sheet (B in Table 2), and the temperature is raised to 45 ° C. It was immersed in the heated zinc phosphate treatment liquid 2 shown in Table 1 for 1 second, washed with water, and dried to prepare a zinc phosphate composite coated steel sheet 2.

[Zinc Phosphate Composite Coated Steel Sheet 3] (C in Table 2) was used instead of (B in Table 2) as the plated steel sheet of the zinc phosphate composite coated steel sheet 2, and Zinc phosphate composite coated steel sheet 2 except that the immersion time is 4 seconds
The same processing was performed.

[Zinc phosphate composite coated steel sheet 5] Degreasing (FC
L4480 (manufactured by Nippon Parkerizing Co., Ltd.), 18 g
Per liter, 45 ° C., sprayed for 120 seconds, and then washed with water (sprayed for 20 seconds) (B in Table 2).
And then subjected to a surface conditioning treatment (Preparen ZN (manufactured by Nippon Parkerizing Co., Ltd.), 1.5 g / liter, room temperature, sprayed for 2 seconds), and then heated to 60 ° C., followed by a phosphating solution shown in Table 1 3 was sprayed for 4 seconds, washed with water and dried to prepare a zinc phosphate composite coated steel sheet 5.

[0084]

[Table 1]

(3) Coating composition (3-1) Organic resin Table 4 shows the organic resin used for the organic film in this example.
In addition, the block urethane-modified epoxy resin described in the same table was prepared by the following method.

Modified epoxy resin (A): A reactor equipped with a condenser, a stirrer and a thermometer was charged with an epoxy equivalent of 1
500 parts by weight of a bisphenol A type epoxy resin (500 parts), 385 parts by weight of xylene, and 385 parts by weight of cyclohexanone were heated and dissolved with stirring. Further, 20 parts by weight of isopropanolamine was added and reacted at 100 ° C. for 5 hours.
3% of 2,4-tolylene diisocyanate and 65 parts by weight of monoisocyanate of an octyl alcohol adduct were added and reacted at 60 ° C. for 5 hours to obtain a modified epoxy resin A having a resin content of 40%.

Block urethane (B): A reactor equipped with a condenser, a stirrer and a thermometer was charged with a molecular weight of about 100.
0, 440 parts by weight of polyethylene glycol, xylene 1
25 parts by weight, heated to 60 ° C. with stirring,
153 parts by weight of tolylene diisocyanate were added. The NCO% of this intermediate was 4.8%. Furthermore, ε-
The reaction was continued by adding 106 parts by weight of caprolactam, and NC was added.
After confirming that the O% was 0, 175 parts by weight of butanol was added to obtain a block urethane B1 as a curing agent having a resin content of 70%. Molecular weight of 40 using similar equipment and reaction conditions
Propylene glycol 500 parts by weight, xylene 300 parts by weight and hexamethylene diisocyanate 42
An intermediate having an NCO% of 1.2% by weight was obtained. Further, the reaction was continued by adding 23 parts by weight of methyl ethyl ketoxime, and after confirming that the NCO% was 0, 77 parts by weight of butanol was added to obtain a block urethane B2 having a resin content of 60%.

(3-2) Rust preventive additives Table 5 shows the rust preventive additives used in the coating composition.

(3-3) Lubricants Table 6 shows the solid lubricants used in the coating compositions.

(3-4) Coating Composition Table 7 shows the composition and coating workability of the coating composition used in this example. The coating workability of the coating composition was evaluated as follows.

[Evaluation of coating workability] When the thixotropic property of the paint is strong, the paint once applied by the roll coater is difficult to flow, so that the roll is likely to remain and a smooth coating film cannot be obtained. Therefore, JIS K5400 4.
5.3 (1990), a TI value (Thi) shown in the evaluation of non-Newtonian properties by a rotational viscometer.
Xotropyindex: rotation speed 6 rpm, 6 rpm
, The degree of thixotropy of the paint was measured, and the coating workability was evaluated.

◎: 0.9 or more and less than 1.3 ： １: 1.3 or more and less than 1.6 Δ: 1.6 or more and less than 3.6 ×: 3.6 or more (4) Rust preventive oil The rust preventive oil used in the examples is shown.

[0093]

[Table 2]

[0094]

[Table 3]

[0095]

[Table 4]

[0096]

[Table 5]

[0097]

[Table 6]

[0098]

[Table 7]

[0099]

[Table 8]

[0100]

[Table 9]

[0101]

[Table 10]

[0102]

[Table 11]

[0103]

[Table 12]

The composition of the surface-treated steel sheet prepared as described above, lubricating properties, powdering resistance, corrosion resistance (corrosion resistance after painting, corrosion resistance after painting), painting properties (paint adhesion, uniformity of electrodeposition coating on the polished part) Table 9 shows the evaluation results of
Shown in

The method of evaluating each characteristic is as follows.

Lubricity The pull-out force under the following sliding conditions was measured, and evaluated by the coefficient of friction = (pull-out force) / (pressure). The evaluation criteria are as follows.

(Sliding conditions) Tool contact area: 50 mm × 10 mm, tool material: SKD
11. Pressure: 400 kgf, Sliding speed: 0.2 m / min (Evaluation criteria): 0.15 or less ○: More than 0.15 and 0.17 or less △: More than 0.17 and 0.20 or less ×: 0. More than 20.

The powdered resistance test material was sheared to a width of 30 mm, and the tip radius of the bead: 0.1.
5mm, bead height: 4mm, pressing force: 500kg
f, After performing a draw bead test at a drawing speed of 200 mm / min, a portion of the bead which was slid was peeled off with an adhesive tape, and the plating peeling amount per unit area before and after the test was measured. The evaluation criteria are as follows.

◎: less than 2 g / m ² +: 2 g / m ² or more and less than 3 g / m ² ○: 3 g / m ² or more and less than 4 g / m ² Δ: 4 g / m ² or more, less than 6 g / m ² ×: Corrosion resistance of 6 g / m ² or more (1) Non-painting corrosion resistance Degreasing the test material (FCL manufactured by Nippon Parkerizing Co., Ltd.)
4460 (immersion at 45 ° C. for 120 seconds), and the end and the back surface were tape-sealed. Then, a corrosion promotion test of the following composite corrosion test cycle was performed, and the degree of red rust occurrence after 6 cycles was evaluated. The evaluation criteria are shown below.

(Composite corrosion test cycle) Salt spray 35 ° C for 4 hours → Drying 60 ° C for 2 hours → 95% RH wet 50 ° C for 4 hours (Evaluation criteria) 錆: No red rust generated ○ +: Red rust area ratio less than 25% ○: Red rust area ratio 25% or more and less than 50% △: Red rust area ratio 50% or more and less than 75% ×: Red rust area ratio 75% or more (2) Corrosion resistance after painting After applying the following three coats to the test material, After performing a cross-cut with a cutter knife and tape-sealing the end and the back surface, a corrosion promotion test of the following composite corrosion test cycle was performed, and the maximum swelling width on one side from the cross-cut portion after 300 cycles was evaluated. The evaluation criteria are shown below.

Coating (3 coats) Zinc phosphate treatment: SD6500MZ (standard conditions) Electrodeposition coating: V20 20 μm thick Intercoat: OTO870 (white color sealer) 35 μm thick Topcoat: OTO647PT (Shaft White) 35 μm (Composite corrosion test cycle) Salt spray 10 minutes → dry 155 minutes → wet 75 minutes → dry 16
0 minutes → 80 minutes wet (Evaluation criteria)）: less than 3 mm ○ +: 3 mm or more and less than 4 mm ○: 4 mm or more and less than 5 mm △: 5 mm or more and less than 6 mm ×: 6 mm or more Paintability (1-1) Paint adhesion 1 After degreasing the test piece, 30
The test piece was immersed in boiling water for 120 minutes, and the coating film was cut into 100 pieces at intervals of 1 mm and cut into 5 m.
m of Erichsen extrusion process, the adhesive tape was adhered to and peeled from the processed part, and the remaining ratio of the coating film was evaluated. The evaluation criteria are as follows.

(Evaluation Criteria) 無 し: No peeling 剥離: Peeling rate less than 3% Δ: Peeling rate 3% or more and less than 10% ×: Peeling rate 10% or more (1-2) Paint adhesion 2 After the three-coat coating shown in 1 was performed, the coating was aged for 24 hours or more after coating, immersed in ion-exchanged water at 50 ° C. for 240 hours, and then the test piece was taken out. Goban eyes at intervals of 100
The pieces were cut into pieces, the adhesive tape was adhered and peeled off, and the remaining rate of the coating film was evaluated. The evaluation criteria are shown below.

Coating (3 coats) Zinc phosphate treatment: SD6500MZ (standard conditions) Electrocoating: V20 20 μm thick Intercoat: OTO870 (white color sealer) 35 μm Topcoat: OTO647PT (Shaft White) 35 μm (Evaluation criteria) ：: No peeling ：: Peeling rate less than 3% △: Peeling rate of 3% or more and less than 10% ×: Peeling rate of 10% or more (2) Uniformity of electrodeposition coating of polished part Half of test material Was polished with emery paper to completely remove the prefoss and the sealing film, leaving the undercoated steel sheet completely exposed, and then subjected to chemical formation: SD6500MZ and electrodeposition coating: V-20. Thereafter, the film thickness of the polished portion and the unpolished portion was measured and evaluated by the difference between the electrodeposition coating film thicknesses of both: (electrodeposition film thickness of unpolished portion) − (electrodeposition film thickness of polished portion). The evaluation criteria are as follows.

(Evaluation Criteria) A: Less than 0.5 μm O: 0.5 μm or more and less than 1 μm Δ: 1 μm or more and less than 3 μm X: 3 μm or more (3) Vividness After the coating was performed, the image clarity was measured by using an image clarity measuring device (ICM-2DP) of Suga Machine Co., Ltd., and the image clarity C was measured using a 0.5 mm slit. The evaluation criteria are as follows.

Coating (3 coats) Zinc phosphate treatment: PB-L3020 (standard conditions) Electrocoating: U-600 film thickness 20 μm Intermediate coating: KPX-36 film thickness 35 μm Top coating: Lugabake B531 film thickness 35 μm (Evaluation Criteria) ：: 80 or more ○: 75 or more and less than 80 Δ: 70 or more and less than 75 ×: less than 70 Weldability CF-type electrode with a tip diameter of 4.5 mm, pressing force of 250 kgf,
Squeeze time: 36 cycles / 60 Hz, energizing time 14
Cycle / 60 Hz, welding current: A continuous hitting test was conducted with a mixed hitting point where the test material and the mild steel sheet were each welded at 25 points each at a current value immediately before the occurrence of dust, and the continuous hitting property was evaluated. The evaluation criteria are as follows.

◎: 1500 points or more ：: 1000 points or more and less than 1500 points Δ: 500 points or more and less than 1000 points ×: less than 500 points

[0117]

[Table 13]

[0118]

[Table 14]

[0119]

[Table 15]

[0120]

[Table 16]

[0121]

[Table 17]

[0122]

[Table 18]

[0123]

[Table 19]

[0124]

As described above, the phosphate composite coated steel sheet of the present invention exhibits excellent lubricity and corrosion resistance, and also has excellent paint adhesion and weldability. It is extremely useful as a surface-treated steel sheet for building materials.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Miyoshi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Masaaki Yamashita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan F-term (reference) in this steel pipe Co., Ltd. BA01 BA04 BA12 BB04 BB06 BB08 BB10 CA16 CA18 CA23 CA39 CA41 DA15 DA16 EB05 EB08

Claims (12)

[Claims] 1. A coating amount of 0.2 to 2.5 g containing at least one selected from nickel, manganese and magnesium as a first layer on the surface of a galvanized steel sheet.
/ M ² of zinc phosphate composite coating layer, and a second
A zinc phosphate composite-treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paintability, characterized by having an organic coating mainly composed of an organic resin shown in the following (1) as a layer. (1) A / B = 95/5 to 50/50 with respect to a modified epoxy resin (A) comprising an epoxy resin, a polyfunctional amine and a monoisocyanate, and a block urethane (B) comprising a polyol, a polyisocyanate and a blocking agent.
Block urethane-modified epoxy resin mixed at a ratio of (nonvolatile content by weight). 2. The zinc phosphate composite coating as the first layer contains at least one selected from nickel, manganese and magnesium, and the total content thereof is 0.1%.
The zinc phosphate composite treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paintability according to claim 1, characterized in that the content is 5 to 8.5% by mass. 3. The corrosion resistance, powdering resistance and lubricity according to claim 1 or 2, wherein the organic film as the second layer contains a solid lubricant and / or a rust preventive additive. Zinc phosphate composite treated steel sheet with excellent paintability. 4. The method according to claim 1, wherein the content of the rust-preventive additive contained in the organic film is a solid content of the block urethane-modified epoxy resin 1
The zinc phosphate composite-treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paintability according to claim 3, wherein the amount is 1 to 100 parts by weight with respect to 00 parts by weight. 5. The method according to claim 1, wherein the content of the solid lubricant contained in the organic coating is a solid content of the block urethane-modified epoxy resin 1
The zinc phosphate composite-treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paintability according to claim 3 or 4, wherein the amount is 1 to 80 parts by weight with respect to 00 parts by weight. 6. A phosphoric acid excellent in corrosion resistance, powdering resistance, lubricity and paintability according to claim 3, which contains hydrophilic silica as a rust preventive additive. Zinc composite treated steel sheet. 7. A rust preventive additive having a specific surface area of 20 to 10
4. The composition according to claim 3, wherein said composition contains 00 m ² / g of silica.
7. A zinc phosphate composite-treated steel sheet excellent in corrosion resistance, powdering resistance, lubricity, and paintability according to any one of items 1 to 6. 8. A solid lubricant comprising polyethylene wax,
8. The method according to claim 3, wherein the resin is at least one selected from a tetrafluoroethylene resin and boron nitride.
The zinc phosphate composite treated steel sheet excellent in corrosion resistance, powdering resistance, lubricity, and paintability according to any one of the above. 9. The solid lubricant has an average particle diameter of 0.05 to 0.05.
The zinc phosphate composite-treated steel sheet according to any one of claims 3 to 8, which is excellent in corrosion resistance, powdering resistance, lubricity, and paintability. 10. The polyethylene wax having a softening point of 1
The zinc phosphate composite treated steel sheet having excellent corrosion resistance, powdering resistance, lubricity, and paintability according to claim 8 or 9, wherein the steel sheet has a temperature of 00 ° C to 135 ° C. 11. An organic film having an adhesion amount of 0.05 to 1.
Corrosion resistance according to any one of claims 1 to 10, characterized in that a 5 g / m ^2, powdering resistance, lubricity, excellent zinc phosphate composite treated steel plate paintability. 12. An adhesion amount of 0.01 to 10 g /
claim 1, characterized in that it comprises an anti-rust oil film layer of m ²
12. A zinc phosphate composite-treated steel sheet excellent in corrosion resistance, powdering resistance, lubricity, and paintability according to any one of items 11 to 11.